When I texture paint when I repeat and tile brush to get smaller it gets worse?
I think that if your target's resolution (image texture being painted on) is low, it will have problems interpreting the projected pixels. If you instead paint on a larger image of at least double the resolution, you will get a better result.

Here I made a 2048x2048 brush, set to repeat like yours and painted into a 4096x4096 target image.